On the application of phase screen models to the interpretation of ionospheric scintillation data

Phase screen models have been used for nearly three decades to facilitate the application of the scintillation theory to data interpretation. Only recently, however, as large amounts of multifrequency phase-coherent beacon data have been analyzed, has the full potential of the model been realized. This paper presents a review of the application of the phase screen model to the interpretation of data from the Defense Nuclear Agency's Wideband satellite (international designation P76-5), which was operational from May 1976 until August 1979. The signal structure and experiment configuration allowed measurements of temporal, spatial, and frequency coherence for a wide variety of scintillation conditions. The derived scintillation parameters are in excellent agreement with the phase screen theory. Moreover, the inferred irregularity structure has been confirmed by recent in situ measurements. The principal results can be summarized with simple algebraic formulas for the scintillation level, spatial/temporal coherence, and frequency coherence or coherence bandwidth. With appropriate manipulations, the formulas fully accommodate the propagation angle dependence in highly anisotropic media.